Anti-viruses are not infallible and often detect false positives. Such is the case for UserBenchmark too, it seems, as the popular free benchmarking tool has been flagged as malware by close to two dozen sites as per VirusTotal.
UserBenchmark is a light freeware that tests your CPU, GPU, memory, storage drives (SSDs and/or HDDs), and USB drives. Some of the recent versions of the software have also included a "Skill Bench" that basically benchmarks the user too.
But as mentioned above, currently, close to two dozen anti-viruses, 23 to be precise, are flagging the software as malware, with the vast majority of these identifying it as a Trojan (image below). The issue isn't completely new as cases such as this are reported by users on forums online.
Microsoft, too, is also in this list of anti-malware programs which flag UserBenchmark as a malicious trojan. According to the Microsoft Security intelligence version 1.353.1394.0, UserBenchmark is "dangerous and executes commands from an attacker". The app has been labeled as a "Severe" threat.
From the screenshot above, it appears that UserBenchmark is being detected as malware due to its Nullsoft Scriptable Install System (NSIS) nature. In fact, NSIS' website states that this is a common false positive issue as many anti-virus programs flag NSIS files as potential malware. But it may indeed be something to be cautioned about since bundling malware inside NSIS packages is also possible.